Hello, I am fairly new to DMR like two weeks ago and just setup my first hotspot with a static IP at the home QTH. I have been having an issue where the hotspot will stop being reachable throughout the day and needs to be rebooted. It will stop responding to web and SSH requests. Sometime it will run for several hours and sometime just for several minutes. Any suggestions where I can stat looking?

Does it still output radio transmissions that originated on the network when the web service fails? That would at least narrow down the problem to the web services. I've seen a few forum users say that RPi Zero W's run out of memory and start unloading services, maybe its nuking the web services.

I would hook a monitor and keyboard up to it and when it fails start checking things directly from a terminal.

When it happens again, can you check if green LED on Raspberry-Pi starts flashing, like there is SD read/write activity, until it stays fully on. At that point Pi-Star seems frozen, but it's not the case, it does partially respond to commands via SSH, if you were already connected.
It happens to me on two different duplex hotspots, both R-Pi 3A+ and both with few months old Kingston 32GB SD cards (20 bucks ones, not some cheap knockoffs)